C-41 Fixer recipe

[HumbleP]

Hi,

I'm about to try my hand for the first time at mixing my own chemicals for DIY c-41.
I have a recipe and most of the chemicals but am sourcing a few others & getting a bit confused.

My fixer recipe calls for "Ammonium Thiosulphate, 60%"
I'm wondering if I can use a different Ammonium product to substitute, as my local photo chemical supplier doesn't seem to have this.

They do however have a number of other ammonium products such as Ammonium Citrate, Ammonium persulphate and ammonium chloride.

Is it possible to use any of these?

My full fixer recipe is:

Ammonium Thiosulfate, 60% 240 mL
EDTA 2 g
Sodium Bisulfite 24 g
Sodium Hydroxide 5 g
Water to 2.0 L

Thanks,
Peter

 

[ME Super]

IIRC, it's the thiosulphate end of the molecule that removes the silver halides from the film.

Since it's C-41, You could do a rehalogenating bleach to convert the silver back to silver halide (thus rendering the dyes visible), wash the film to wash out the bleach, and then run it through a straight B&W fix.

 

[Gerald C Koch]

No, you must use ammonium thiosulfate. It is the thioosulfate ion which removes silver halide from the emulsion. This chemical is available both as a 60% solution and as a solid.

 

[brucemuir]

You need a thiosulphate.
Either a Sodium Thiosulphate which is a powder/crystal and generally slower acting whereas the ammonium thiosulphate is usually a liquid.

If you can find sodium thiosulphate (usually easier to find than ammonium thiosulphate) you will need to adjust the amount in your formula.

If you can tell us where you are located we could proceed to suggest some possibilities.
Sodium thiosulphate is used in swimming pools and can sometimes be sourced from a pool supply place.

 

[HumbleP]

Oh great....thanks everyone for the response.
Do you know the difference (ratio) I need of Sodium instead of Ammonium?
I noticed sodium is available at Vanbar.
I'm in Sydney

 

[brucemuir]

I'll let Gerald or someone more knowledgeable fill you in on how you figure the differences in quantities.

 

[polyglot]

Rapid Fixer concentrate is basically 60% Ammonium Thiosulfate (that's as much as will dissolve in water reliably) with some buffering agents, i.e. the sulfite and hydroxide that that recipe calls for. You may or may not need to add the EDTA, but B&W Rapid Fixer should work with C41. The lower concentration recommended by that recipe is because C41 has a lot less silver to strip out than traditional B&W film; the density is produced by dyes instead.

Don't use sodium thiosulfate, it will be a far slower fixer.

Edit: sorry, it depends which one you buy. Most rapid fixers are acidic and the buffers included with them differ. Ilford sells both Hypam and Rapid Fixer with the same thiosulfate content in each but different buffering arrangements. Only the Hypam is compatible (due to a different pH) with hardeners, which means that one or the other may or may not be compatible with your use of EDTA.

 

[Athiril]

Modify pH to 6.5 if using a b&w fixer, which would what the last 2 ingredients would be for.

You can make thiosulphate, from a sulphite and granulated sulphur (Cheap at the garden supply section), heated in water (sulphur doesn't dissolve on its own in water, so when it does start to, you know the reaction is starting).

 

[HumbleP]

Thanks for that detail. I'm wondering when you said "It depends which one you buy" did you mean which Sodium thiosulfate you buy?
Also, one supplier I've sourced has "Ammonium Thiosulphate, 98%" What does that actually mean compared to
"Ammonium Thiosulphate, 60%"?

 

[polyglot]

"Which one" being which brand of premixed Rapid Fixer. They all contain the same ammonium thiosulfate, which is always ammonium thiosulfate. The difference is in the buffering, i.e. those other ingredients that are included.

The 98% is possibly a solid.

 

[Athiril]

Thanks for that detail. I'm wondering when you said "It depends which one you buy" did you mean which Sodium thiosulfate you buy?
Also, one supplier I've sourced has "Ammonium Thiosulphate, 98%" What does that actually mean compared to
"Ammonium Thiosulphate, 60%"?

The 98% is fine, and would save on shipping, compared to 60%, getting more of it per kg of shipping.

 

[pinholer]

The 98% should be in powder form whereas the 60% will already be in liquid form.